Method of etching printing plates and composition of matter for use in connection therewith



' Patented Feb. 28, 1928. l I I I UNITED STATES PATENT OFFICE.

FRITZ TUTZSCHKE, OF LEIP ZIG-SCHONEFELD, GERMANY.

METHOD OF ETCHING PRINTING'IELATES AND COMPOSITION OF MATTER FOR USE IN CONNECTION THERE-WITH.

No Drawing. Application filed February 17, 1927, Serial No. 169,137, and in Germany February 22, 1926.

My invention refers to a method of etchtory treatment with acid before etching can ing lithographic print-ing plates consisting be dispensed with. Plates treated in accord- 35' of aluminium or an alloy of this metal. It ance with this invention will result in paralso includes a composition of matter for use ticularly clear prints and can be used for in connection with the new method. printing very large numbers of copies.

According to the present invention the Various changes may be made inthe decorrectetching of lithographic printing tails disclosed in the foregoing specification 40 plates made of aluminium or an al min- Without departing from the invention or sacium alloy is rendered possible by the use rificing the advantages thereof. of a corrosive agent containing calcium I claim:

nitrate and potassium dihydrogen phosphate 1, A a new o o ition f tt r fo e (KH POQ. i in preparing aluminium printing plates a 45 I havev found that by etching aluminium wat r ol tio of calcium nitrate and poplates or plates consisting of an aluminium t iu dihydrogen phosphate (KI-LPQQ- alloy with a corrosive agent consisting of or 2. A a new composition of matter for use containing calcium nitrate and potassium diin preparing aluminium printing plates :1 hydrogen phosphate I am enabled to btain watery solution of calcium nitrate and potasr perfect etchings. sium dihydrogcn phosphate (KH POjQ in In practising my invention I have, for in the proportion of 100 parts by Weight calstance,usedasolution of 100 parts by weight cium nitrate and 60 parts potassium dihyof calcium nitrate and 60 parts of potassium drogen phosphate to 1500 parts water. dihydrogen phosphate in 1500 parts of wa- 3. As a new composition of matter for use 55 ter. in preparing aluminium printing plates a I have further found that in certain cases watery solution of calcium nitrate and potasan addition of gum arabic or of arabine. is sium dihydrogen phosphate (KH PO to advantageous, and I have, for instance, addwhich some gum arabic is added. ed to a solution as above described parts 4. The method of preparing metal printof gum arabic or 5 parts arabine. ingplates containing aluminium, compris Before applying the new .corrosive solu,-' ing acting on the plates with a corrosive 30 tion I prefer treating the metal plates with agent containingcalcium nitrate and potasgrinding sand to which some potassium alum sium dihydrogen phosphate. has been added. In testimony whereof I afiix my signature. Washing of the plates and the prepara- 'FRITZ TUTZSCHKE. 

